Thursday, October 30, 2008

Ethanol Thoughts

For some reason, I've been thinking of ethanol fuel lately. Perhaps I heard Obama or McCain mention it, or maybe I saw a car w/a bumper sticker.

Either way, I started thinking about it - and what struck me was the question of where the biomass (corn/soy/switch-grass) was going to come from.

Ignore for a minute the fact that even if we turned all the corn/soy we grew into fuel - we still wouldn't have enough gas to run our vehicles. Ignore for a minute the fact that nobody has come up with a cost-effective (and efficient) method of converting biomass into fuel.

Where is this biomass coming from?


Ok. Fine.

What do all farmers know? They know that to get something out of the ground you need: water, light, seed, and nutrients. After a few generations of anything, you need to feed the soil. Where is the fertilizer going to come from? You can't compost - you just turned all the biomass into fuel. You need fertilizer - and that's going to increase the cost. People talk about using switchgrass - and that it is responsible for the fertile soil in the Midwest. Yes, it's how we got such fertile soil - by having switchgrass grow there for generations - not by harvesting it twice every year.

Yes, stuff grows in the ground, but it's not an unlimited bank account. This is something everyone knew before the industrial revolution. But now ... people think you only have to harvest/harvest/harvest.


Also, to get an idea of the scale of the problem, I was reading this article: The Oil Drum | Cutting Through the Coskata Cellulosic Ethanol Hype, and it breaks down an analysis of a particular company's claims. The part I found most interesting was the quantity of biomass required:
In Coskata's case, they promise 100 gallons (+) per ton. How much biomass then to run a 100 million gallon per year facility? A million tons per year. How much biomass is this? If we return to the Douglas fir example, it is the biomass equivalent of around 1.2 million mature Douglas firs per year.
To put in the context of rail cars, the coal cars lined up outside of a coal-fired power plant are a familiar site. According to this, each car carries about 100 tons of coal. For a million tons of coal a year, you would have to have 1 million/(100 tons per car) = 10,000 cars per year coming into and leaving the plant. That's more than a car an hour, 24 hours a day, 365 days a year. And of course coal is quite a bit denser than biomass, so more cars would be required in the case of biomass.
Wow, a train car every hour, every day, to produce ... 100 million gallons of ethanol. That's a lot of biomass. But 100 million gallons is a lot, isn't it? No: we use 390 million gallons of gas per day. And, that's ignoring the fact that ethanol only has 2/3 the energy of gasoline.

How are you going to solve the logistics of getting that much biomass shipped around? To cover all the gas we use in vehicles we'd need nearly 1500 such ethanol plants, each requiring at minimum - one train car full of biomass every hour.

The numbers are simply staggering.

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